libeasy: check for errors in strtob()

libeasy/utils.c

@@ -41,7 +41,19 @@ static int hex2byte(const char *hex)
 
 LIBEASY_API uint8_t *strtob(char *str, int len, uint8_t *bytes)
 {
-	size_t i;
+	size_t slen;
+	int i;
+
+	if (!str || !bytes)
+		return NULL;
+
+	slen = strlen(str);
+	if (!slen || slen % 2 || str[slen] != '\0')
+		return NULL;
+
+	slen >>= 1;
+	if (len > slen)
+		len = slen;
 
 	for (i = 0; i < len; i++) {
 		int a;
@@ -60,7 +72,7 @@ LIBEASY_API char *btostr(uint8_t *bytes, int len, char *str)
 {
 	size_t i;
 
-	if (!str)
+	if (!str || !bytes)
 		return NULL;
 
 	for (i = 0; i < len; i++)

libeasy/utils.h

@@ -16,9 +16,9 @@ extern "C" {
  * "001122334455" --> {0x00, 0x11, 0x22, 0x33, 0x44, 0x55}
  *
  * @param[in] str hex string.
- * @param[in] len string length of the hex string.
+ * @param[in] len length of output buffer passed to the function.
  * @param[out] bytes output buffer to write the converted hex string.
- * @return byte array of the converted hex string.
+ * @return byte array of the converted hex string, or %NULL on error.
  */
 extern uint8_t *strtob(char *str, int len, uint8_t *bytes);
 
@@ -31,7 +31,7 @@ extern uint8_t *strtob(char *str, int len, uint8_t *bytes);
  * @param[in] bytes byte array.
  * @param[in] len length of the byte array.
  * @param[out] str output buffer to write the hex string.
- * @return hex string.
+ * @return hex string or %NULL on error.
  */
 extern char *btostr(uint8_t *bytes, int len, char *str);